Control device



July 18, 1939. J. M. JACKSON CONTROL DEVICE Filed Feb. 21, 1938 Gum/M1 4 Patented July 18, 1939 UNITED STATES PATENT OFFICE 6 Claims.

This invention relates generally to automatic control means and particularly to control means for stopping the operation of a pump actuating mechanism, which includes a walking beam, in

5 the event the movement of the mechanism becomes accelerated or irregular.

This invention is particularly designed for use in combination with the walking beam of a typical well pumping mechanism and the inven- 10 tion will be illustrated and described in this connection, however the invention might be used with other types of actuating mechanisms without departing from the scope of the invention.

Pumping mechanisms, particularly oil well 15 pumping mechanisms, are operated unattended for long periods of time. The continual stress of raising oil, often from great depths, renders the mechanism subject to breakage. When a breakage occurs, which quite frequently hap- 2 pens, it often results in considerable damage to the pump actuating mechanism or to the pump itself, due to the fact that the motive power continues operating, thereby moving the actuating mechanism and the broken parts, often at an 25 increased speed. The motion of the Walking beam either accelerates or becomes irregular or eccentric as the result of the continued application of power to it after the breakage of some part. It may also happen that the pumping 30 mechanism will stick, in which event the movement of the mechanism will be slowed down and the belt connecting the motor and the rest of the mechanism will slip, resulting in irregularity of movement of the walking beam and the 35 creation of a fire hazard, the friction of the slip ping belt overheating the belt and its driving and driven pulleys.

It therefore is a primary object of this invention to provide a control device which may be 40 mounted on a walking beam or some other member of a pump actuating mechanism which is effective to stop the operation of the motive power for the pump mechanism when the action of the part on which the device is mounted be- 45 comes accelerated, irregular or otherwise eccentric, due to failure of a part or parts of the pump or pump actuating mechanism.

It is also an object of this invention to provide a device of the character indicated which is 50 entirely automatic in its operation and which may be easily and quickly reset for operation after it has been actuated.

It is a particular object of this invention to provide a control device for mounting on a walk- 55 ing beam which includes a mercury switch adapted to automatically close a circuit when the movement of the walking beam becomes accelerated or irregular. It is a further object of this invention to accomplish the closing of the switch Without formation or passage of sparks or open 5 arcs and thereby eliminate any fire hazard in connection with the operation of the switch. To accomplish this object a hermetically sealed switch is employed.

It is a further object of this invention to provide a control device which can be connected in circuit with any suitable motor stopping means so that when the switch of the control device is closed the motor stopping means will function to stop the motor, or motive power, irrespective of the type of motive power employed. In this connection the control device might also be connected with a warning device, such as a light, bell or horn, in place of or in addition to connection to a stopping means.

It is also an object of this invention to provide a device of the type indicated which is not dependent upon the functioning of bearings, levers, weights, or the like for operability and which requires no lubrication, maintenance or periodic inspection service.

It is also an object of this invention to provide a device which may be adaptable to the eccentricities of the particular beam with which it is to be associated.

Finally, it is a further object of this invention to provide a device of the type indicated which is in the form of a single compact dependable instrument and is simple and inexpensive to manufacture, and which can be easily installed for use.

These and other objects will be apparent from the accompanying drawing and the following description thereof. Referring to the drawing, which is for illustrative purposes only,

Fig. 1 is a diagrammatic elevation of oil well pumping mechanism showing the relation of the invention to the mechanism.

Fig. 2 is a front elevation of the device of this invention shown with the door of the device open.

Fig. 3 is a sectional elevation taken on line 3-3 of Fig. 2.

Fig. 4 is a sectional elevation of the mercury switch.

Fig. 5 is a View similar to Fig. 2 but showing the device tilted for resetting.

Fig. 6 is a fragmentary sectional elevation of another form of switch.

More particularly describing the invention,

referring to Fig. 1, numeral I I generally indicated an oil well pumping mechanism including generally a prime mover l 2 which is shown diagrammatically as an internal combustion engine, a belt l3 connecting the motor to the reduction gear unit M which drives a counter balanced crank E6. The crank l6 operates a walking beam I! through the medium of a pitman l8. The beam is supported by a Sampson post l9 and carries the horsehead 20. An oil Well, indicated by reference numeral 2|, is pumped by means of pump rod 22 connected to the horsehead by the cable 23. The pump itself is below the surface of the ground and is not shown.

Reference numeral 25 generally indicates the control device of this invention which is mounted on the walking beam and is connected to a motor stopping means of motor I2 by insulated wires 2623. In the case of the internal combustion engine shown, the wires might lead to a magneto so that when a circuit is completed through the wires the magneto will be grounded or short circuited and stop the motor.

Referring to Figures 2-5 for the details in the construction of the device, the device comprises a box 30 which may be fabricated from sheet metal provided with a corrosive-proof coating or it may be made from other suitable material. The box 30 is provided with brackets 3| by means of which it may be attached to the walking beam by any suitable attachment means approximately in the position shown in Fig. 1. A door 32 (fragmentarily shown) is provided which is hingedly mounted at 33 and adapted to be closed over the open front of the box and fastened by a catch 33'.

Mounted interiorly of the box is a mercury switch generally indicated by numeral 34. The switch is made of glass and comprises a hollow bulb portion 35 which has a tubular shank 36 mounted in a Bakelite base 31. As a continuation of the shank 36 there is an upwardly extending tubular portion 38 which, with the portion 36, forms a Well or collector stem 39. In the bottom of this shank portion 36 and extending through it into the collector stem 39 are switch terminals 42-42. The mercury switch is adapted to be filled with mercury 43 to approximately the height indicated in Fig. 4. In this position the mercury lies in the bulb portion 35 surrounding the upwardly extending tubular portion 38 in an annular body and slightly below the top of the upwardly extending tubular portion 38. The top of the bulb portion 35 is preferably conically disposed so as to deflect the mercury into the collector stem when the mercury is thrown against the top of the bulb portion.

For mounting the switch in the container 30 there is provided a bracket, generally indicated by reference numeral 45, which is mounted on a bolt 46 extending through the rear portion of the box 30. This bolt is provided with the nuts 4! and suitable spacing washers 48. The front downwardly extending portion 50 of the bracket 45 has mounted thereon the clips 52 for mounting the mercury switch 35 on the bracket. These clips each comprise a metal band 53 which encircles the base 31 of the switch. The ends of the strip 53 are secured by the screws 55 and are mounted on the front portion 59 of the bracket 45 by means of the screws 56 and nuts 51.

To facilitate connecting the mercury switch to suitable insulated wires 60 there is provided an insulated terminal plate 6| which is mounted on the front portion 50 of the bracket 45 by means of metal strips 62. The metal strips are attached to the plate 6| by screws 63 and to the portion 50 of bracket 45 by screws 64.

The terminal plate 6| is provided with terminal screws 65 and 66 for attaching the insulated Wires 26-26. On the rear side of the plate 61 wires 61 and 67', which lead from the terminals 4242, are attached to the terminal screws 65 and 66 respectively.

Assuming that the device is to be connected to the magneto of an internal combustion engine the insulated wires 26-46 would lead thereto as suggested in connection with Fig. 1. It is to be understood that the wires could lead to any form of motor stopping means which could be electrically actuated.

The bracket 45 is mounted for rotative movement on the bolt 46 and for the purpose of yieldably holding the bracket 45 in the position in which it is shown in Figures 2 and 3, that is, the normal position of the bracket, there is provided the spring means 10 which is attached to the lower end of the rear portion ll of the bracket 45 by means of screw 12 and nut 13. The spring means is attached at each end to the sides of the box 30 by means of the screws 14 and 15 respectively. Other types of spring means for yieldably holding the bracket might be used, however. For convenience a handle portion 16 is provided on bracket 45 to facilitate rotating the mercury switch to the position in which it is shown in Fig. 5 for the resetting of the switch.

Assuming that the well pumping mechanism is to be operated by an internal combustion engine of the type requiring a spark for ignition, the Wires 26-26 of the device are connected to the magneto of the motor so that if a circuit is completed through these wires it will short circuit or ground the magneto and cause the motor to stop.

The mercury switch is tilted to the position shown in Fig. 5 so as to insure all of the mercury being out of the collector stem 39 and in the bulb portion 35 of the switch. When the switch is then rotated to the normal set position of Figures 2 and 3 the mercury will be entirely in the bulb portion 35 of the switch surrounding the tube 38, as particularly shown in Fig. 4. When the mercury is in this position there is no possibility of contact with the switch terminals 42-42. As the walking beam reciprocates, the regular motion thereof is not suflicient to disturb the mercury to the extent of causing it to enter the collector tube 39. In the event that the movement of the walking beam becomes accelerated or irregular due to breakage of a part of the pump or part of the pumping mechanism, this irregular or accelerated motion of the Walking beam will cause some of the mercury to be thrown against the conical top of the bulb portion and be deflected into the collector tube 39 and contact the switch terminals 42-42', closing the switch, thereby completing a circuit through the magneto and stopping the motive power.

When it is desired to reset the control device the switch is manually tilted or rotated to the position shown in Fig. 5, thereby causing mercury entrapped in the collector stem to flow outwardly therefrom and into the bulb portion of the switch. The switch is then moved to the upright position of Fig. 2 and is again ready for operation.

As suggested above, the wires 26-26 might be connected to any form of stopping means for use with the particular motive power employed.

It is unnecessary to adjust the amount of mercury in the switch or any other element of the switch to the particular installation. The eccentricities of various walking beams may be compensated for at the time of installation of the box on the beam. The distance from the pivot point of the beam to the point of mounting of the box may be varied to suit the action of the particular beam.

In the drawing the mercury switch has been shown as made of glass, but it is to be understood that the switch might be made of some other materal, as for example Bakelite or the like.

In Fig. 6 there is shown a modified form of switch, generally indicated by reference numeral '18, wlL'ch has a partition member 19 forming a mercury cup 80 in the upper portion of the switch. In this form of the switch, mercury is retained in the cup 80 during normal operation of the walking beam and is splashed out of this cup and into the well or collector stem, here indicated by reference numeral 8|, and which has the switch terminals therein at the bottom as in the form of switch particularly illustrated in Fig. 4 when the action of the walking beam becomes irregular or eccentric. It is within the scope of this invention to utilize other forms of mercury switches, and the invention should not be limited to the particular forms of switch illustrated.

I claim as my invention:

1. For use in a device of the class described, a mercury switch comprising a hollow bulb portion having a conical-shaped top, a downwardly extending tubular shank portion, an upwardly extending tubular member in said bulb portion together with said shank portion forming a well, a pair of switch terminals having exposed portions at the bottom of said well, a pool of mercury normally contained in the bulb portion about said upwardly extending tubular member, the conical-shaped top of said bulb portion being adapted to deflect mercury into said upwardly extending tubular member to contact said terminals when the mercury is thrown against said conical-shaped top of said bulb portion by jarring of the switch.

2. For use in a device of the class described a mercury switch comprising a hollow bulb portion, a downwardly extending tubular shank portion forming a well, a pair of switch terminals having exposed portions at the bottom of said well, a partition member extending upwardly interiorly. of the bulb portion and forming a cup and a pool of mercury normally contained in said cup, said mercury being adapted to be thrown from said cup to a position where it may enter said well to connect said terminals when said switch is sufiiciently jarred.

3. A switch for use as described comprising a sealed receptacle of insulating material having a hollow bulb portion and a hollow stem communicating with said bulb portion, a pair of switch terminals at the lower portion of said stem, means in said bulb portion forming a barrier between a portion of the bulb portion and said stem, and a mobile metallic body normally contained in said bulb portion behind said barrier.

4. A switch for use as described comprising a sealed receptacle of insulating material having a hollow bulb portion and a hollow stem extending into said bulb portion, the upper end of said stem being intermediate the top and bottom of said bulb portion, a pair of switch terminals at the bottom of said stem, and a. mobile metallic body normally contained in the bulb portion at a level below the top of said hollow stem.

5. In a control device: a supporting member; a mercury switch comprising a sealed receptacle of insulating material having a hollow bulb portion and a hollow stem communicating with said bulb portion, a pair of switch terminals at the lower portion of said stem, means in said bulb portion forming a barrier between a portion of the bulb portion and said stem, and a mobile metallic body normally contained in said bulb portion behind said barrier; means for frictionally rotatably supporting said switch on said supporting member; said switch being adapted to be set by rotation of said switch to a substantially inverted position and returned to an upright position whereby the mobile metallic body is caused to move out of said stem to a position behind said barrier.

6. In a control device: a housing; a bracket rotatably mounted in said housing, means for yieldably holding said bracket in an upright position; and a mercury switch mounted on said bracket, said switch including a hollow bulb portion and a hollow stem extending into said bulb portion to a point above the bottom of said bulb portion, a pair of switch terminals at the bottom of said stem, and mercury normally contained in the bulb portion at a level below the top of said stem, said switch being adapted to be set so that the mercury is out of contact with said terminals when said switch and bracket are rotated through a portion of a revolution and returned to an upright position.

JOHN M. JACKSON. 

